This application relates to a developer cartridge that holds a developer therein. This application also relates to an image forming unit and an image forming apparatus that include the developer cartridge.
A developer cartridge has an opening at its bottom portion, which extends in the longitudinal direction of the cartridge, to supply a developer to an image-forming unit. The cartridge also has a shutter to open and close the opening. The shutter is rotatable around a rotational axis, which extends in the longitudinal direction along an inside wall of the cartridge surrounding the opening. The shutter has a sealing member that covers the opening so as to prevent the developer from leaking from the cartridge when the shutter keeps the opening closed. Japanese Laid-Open Patent No. 2006-243446 discloses one such developer cartridge.
In such a developer cartridge, however, the opening is liable to be deformed by an external force when the cartridge, which is mounted on the image-image forming unit, is replaced with a new one. The deformation of the opening causes gaps to form between the opening and the sealing member, resulting in the leakage of the developer from the opening through the gaps.